To prevent damage to, and malfunction of, electronic devices caused by electro-static discharge (ESD), various types of ESD protection circuits are currently used. ESD protection circuits are circuits that protect a subsequent electronic circuit from ESD by transferring ESD to the ground or the like. For example, an ESD protection circuit is disposed between a signal line and the ground (or earth).
For example, Patent Document 1 (identified below) discloses an electronic device in which, as a protective measure against ESD, a filter circuit having an ESD protection function is provided in the vicinity of an antenna terminal.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2008-54055.
However, mounting a plurality of discrete components on a mount board to form a circuit having an ESD protection function, such as that described in Patent Document 1, requires a large mounting area. Moreover, since wiring for connecting the discrete components is formed on the mount board, the resulting increase in wiring length also causes an increase in parasitic inductance, which may make it difficult to achieve required characteristics.